Conventional cosmetic compositions are usually in the form of emulsions either of the water-in-oil (W/O) or oil-in-water (O/W) types. O/W emulsions are usually preferred in the cosmetics field, because O/W emulsions typically have a fresher, less greasy, less tacky, and lighter feel than W/O emulsions. As W/O emulsions are close to the skin's hydrolipid film, they are more effective from a dermatological viewpoint by promoting long lasting moisturizing efficacy by providing an occlusive film and reinforcing the active ingredients into the stratum corneum. Unfortunately, their tackiness, greasiness and poor spreadability render them less appealing to consumers.
There is growing consumer demand for cosmetic products which provide anti-aging skin care benefits such as diminishing the appearance of and/or preventing wrinkles, fine lines, skin laxity, and discolorations or improving skin radiance. Unfortunately, many of the active ingredients which are used in these products are difficult to formulate into stable cosmetic compositions, especially at concentrations required for efficacy. Moreover, even when these ingredients are formulated into stable cosmetic compositions, these compositions may not appeal to the consumer because of tackiness, greasiness, and poor spreadability.
Capryloyl salicylic acid is an amphoteric active ingredient used in cosmetic compositions for anti-aging. Unfortunately, its amphoteric nature results in the destabilization of W/O emulsions making it difficult to prepare stable W/O emulsions which contain high levels of capryloyl salicylic acid.
Another anti-aging active ingredient used in cosmetic compositions is hydroxypropyl tetrahydropyrantriol. Unfortunately, due to its high electrolyte content, it too presents a formulation challenge, particularly in direct O/W emulsions, by requiring high concentrations of water phase thickeners in order to achieve a stable viscosity.
The use of high levels of these types of active ingredients presents severe stability challenges when formulating cosmetic compositions, especially W/O emulsions.
FR 2 911 496 B1 describes a W/O emulsion comprising 0.3% capryloyl salicylic acid and a wax. The emulsions obtained, however, are in the form of a hard solid having a penetration force of greater than or equal to about 40 grams. It may be postulated that the stability of this emulsion is attributed to its solid state in which the capryloyl salicylic acid is suspended in the wax matrix. These types of hard solid emulsions suffer from undesirable attributes such as poor glide and a waxy texture.
It is therefore an objective of the present invention to provide W/O emulsions which are fluid in nature, include amounts of anti-aging ingredients that were not previously possible due to stability concerns, and possess a pleasant sensorial experience when used by consumers.